“That’s queer,” said Dick. “Looks as if the spook-train ran only from here to Olly’s Yard and back. But why? And where in the world is it now? It’s vanished into thin air!”

Julian was as puzzled as Dick. Where could a train be if it was not in the tunnel? It had obviously run to the middle of the tunnel, and then stopped — but where had it gone now?

“Let’s go to the mouth of the tunnel and see if the lines are bright all the way,” said Julian at last. “We can’t discover much here — unless the train suddenly materialises in front of us!”

They went on down the tunnel, their torches flashing on the lines in front of them. They talked earnestly as they went. They didn’t see four men waiting for them, four men who crouched in a little niche at the side of the tunnel, waiting there in the dark.

“Well,” said Julian, “I think — — ” and then he stopped, because four dark figures suddenly pounced on the three boys and held them fast. Julian gave a shout and struggled, but the man who had hold of him was far too strong to escape from. Their torches were flung to the ground. Julian’s broke, and the other two torches lay there, their beams shining on the feet of the struggling company.

It didn’t take more than twenty seconds to make each boy a captive, his arms behind his back. Julian tried to kick, but his captor twisted his arm so fiercely that he groaned in pain and stopped his kicking.

“Look here! What’s all this about?” demanded Dick. “Who are you, and what do you think you’re doing? We’re only three boys exploring an old tunnel. What’s the harm in that?”

“Take them all away,” said a voice that everyone recognised at once.

“Mr. Andrews! Is it you?” cried Julian. “Set us free. You know us — the boys at the camp. And Jock’s here too. What do you think you’re doing?”

Mr. Andrews didn’t answer, but he gave poor Jock a box on the right ear that almost sent him to the ground.

Their captors turned them about, and led them roughly up the tunnel, towards the middle. Nobody had a torch so it was all done in the darkness and the three boys stumbled badly, though the men seemed sure-footed enough.

They came to a halt after a time. Mr. Andrews left them and Julian heard him go off somewhere to the left. Then there came a curious noise — a bang, a clank, and then a sliding, grating sound. What could be happening? Julian strained his eyes in the darkness, but he could see nothing at all.

He didn’t know that Mr. Andrews was opening the bricked-up wall through which the train had gone. He didn’t know that he and the others were being pushed out of the first tunnel into the other one, through the curious hole in the wall. The three boys were shoved along in the darkness, not daring to protest.